1. Field of the Invention
The invention concerns composite bearing races, the material of the body of the race differing from that forming the ball groove.
2. Description of the Prior Art
Bearings are known in which at least one of the races consists of two continuous metal rings concentric with one another and one shrunk on the other. These rings may be of different alloys heat treated in different ways to confer mechanical properties to them corresponding to their functions. Thus a ring with a ball groove would have a high degree of hardness, while an outer ring would have a lower degree of hardness to facilitate machining.
The problem left unsolved by this type of bearing resides in the fact that the axial immobilization of the ring with the ball groove cannot be guaranteed with sufficient precision when the balls, disposed between the races, are subjected to simultaneous axial and radial forces. To remedy this defect, it has been attempted to make ball bearing races in the form of a ring into which is screwed a race, the periphery of which constitutes a ball groove. This race does not allow the use of conventional materials, satisfactorily hardened by appropriate heat treatment. It is known, in fact, that the heat treatment envisaged (tempering, case hardening) always superficially deforms the threaded race so that correct fitting of it in the ring proves to be difficult, if not impossible. This is due to the fact that the steels making up the races no longer have, after their heat treatment, the characteristics of resilience and tenacity necessary for mechanical strength of the threads.